Method of attaching soles to shoes



p .4 H. E. MARASCO METHOD OF ATTACHING SOLES T0 SHOES Filed March 14, 1944 Harahi EMarasao Afiarizqy Potented Sept. 25, 1945 UNITED 2,%5,523 METHOD OF ATTACG SOLES TO SHOES Harold E. Morocco, Swampscott, Mm, Mach to Compo Shoe nor lnery Corporation, Bolton,

Moon, n corporation of Delaware Application ltlorch M, 1944, Serial No. 528,370

2 ifilnlnnn.

This invention relates to the manufacture of iootweor and more specifically to methods of treating and attaching cemented outsoloa to shoes.

More particularly the invention relates to a method or permanently attaching outsolcs to shoeo by means of a thermoplastic content which is hoot softened or activoted" by on olcctrostotic field produced between electrodes conncctcd to n high irequency senerator.

In cement attochingoutsolec to shot bottoms it has been proposed to coat the nttnching moon of tho shoe bottom and outsole with n thouplastic cement in solution with to solvent; allow the solvent to evaporate so thnt the cement is substantially dry and non-tncky; and, then bring the parts together and position then: in o shoe press, having electrodes iissoclhtod with its sole pressing pad, so that the adhesive on tho outsole and the adhesive on the shoe bottom ore included in the electrostatic field produced loctwccn tho electrodes and am simultaneously hoot ed and activated thereby. In thcsc proposed methods at least one of the electrodes must be ottochcd to and must follow the dilation pad as it conforms to various slow and chnncs oi choc being processed, o thin iuontly mndto in breakage of the electrode material tailor n com parotively few shoes are processed nscing oc curs which damages the shoo and tho solo nreso inz pod. Furthermore, inclusion of the choc in l the electrostatic field sources rcsulto in or ratio heating of the ccmcntcd nrcnc, when moinl objects within the shoe such on looting toclzs or staples, shank stifieners, or oven nlctol nitric oi the last within tho shoc, concetc thoflolo and cause overheating in some places to the con tent that the outsolc leather is normnnmtly m lured. In cases where one oi tho olec is within the shoe i. e. in or on the c or oi tachcd to the lost bottom, some of the looting tacks or staples may contact sonic form it part of the electrode, thus reducing tho wooing between the electrodes, and then arcing occurs which burns n hole through the outsole ot the point or points where the tacks are located.

Inclusion of the shoe in the electrostatic field also heats the entire shoe bottom so that ofterthc current is shut on the shoe must remain under pressure in the cross for o, consideroble period of time in order to allow it and the ndhcoivs to cool to a point where the shoe con sofcly he removed without tho'dnngcr of the outsolc sprin in; any from the upper.

of tho oolo orccoinc odhesive must he Another drawback oi inclu tho sh in tho on electrostatic field is thot it delays production until the bottom filler material of the shoe is dry, no any excessive moisture therein causes ates to such an extent that the outsole becomes o aged by heat and at v '1' l.

Still another disadvantage in activating tho adhesive on the outsole and shoe bottom no they are in the shoe press is that the frequency of the current required to produce an olcctro static field of sumcient strength to activate the in the order oi oevcr'nl moon cycles, thus it is diiflcult to tronsicr it to tho choc presc electrodoc without high loccoo; and, on the sole pressing pods, with which at lonst onc oi the electrodes must ho cssocintcd, nro oi lenthcr or rubber they hnvo scold dielectric proportion at these high frequencies nod therefore concnnio much of the power from the electrodes.

I hove found that the above nnd othcs dilllollh ties are avoided by my novcl method oi ottnch= inc solo to chosc horcmoltcr cnnloincd.

ahccordincly, s principal object of tho invention is to provide on improved 'lnothosl of not soles; to 'shocc with o thermonlnstic cemcnt. whorchy the ccmcnt is octlvotcol by tho mom of on electrostatic field Without m choc bottom.

Another ohjoct of the invention is to provide n method of nttnchino soles to show with o theoplootlc cement which is hoot ootivotod hit the influcncc of on olcctroctctic hold, Whelchn hcctcd cement is mplo'ily cooled, thus, rcducinc the setting time of th cornont; rcdnclng tho tllnc the shoe must he ltcht undcr prcssuni d consot: reduc the nbcr oi choc nscssw ncc csscry to promo shoot on o production hosis, ond rcsuitins in considccnhlo cos in mnntllociroc cud en olncnt.

A further object of the invention is to movidc c thou oi opcodlno up tho cement ottochmcnt of soles toshooc whilo nrcventino; common to shoes and the solo cttochlns content.

A still further object oi tho invention to provide a method of attaching solos to shoo with n thermopic cohesive log? nctivotc tho and hesive in on elcctrootstic field produced lot on norotus thot is oi simple construction, chow and cmcient to opcmtc and which can he wood with present choc crossing equipment.

Other objcctzl of the invention will in unit ho obvious and will; in port copcor hcrcinoiton Tho invention accordingly comprises the covornl storm sud tho zclotion oi one or mom of ouch stem with respect to men oi the otllorti, chill the lotus cmbotiyino lccco cl trodes i and 26 so that on combinstion or elements end errtussement of ports which ere adopted to edect such step ell For 9. fuller understanding of the nature and objects of the invention reference should be had to the following detailed description taken in connection with the accompanying drewins, in which:

Fig. 1 is e. sectioned view, of a preferred form of apparatus ior use in carryin out my novel method, token substantially along: lines i-i oi File. 8;

Fig. 2 is e plan view of the apparatus embodyins features of my invention; and

Fig. 3 is 2. front elevation of the apparatus and showing outsoles being treated thereby prior to etteehment to shoes.

Referring to the drawing, it will be seen that a suitable and preierred form of apparatus for use in practising my novel method of attaching soles to shoes comprises e. cabinet or electrode support it, which me? be mounted on a. suitable stand near or attached to a. shoe pressing machine preferoble of the type shown in the patent to Smith, No. 2,204,336. A metallic cover H is secured by the screws ii to the rear of the cabinet so that the lower portion thereof is fully enclosed, and housed therein is s. high frequency electronic oscillctor id to which current is supplied by the lead it passing through at grommet in the cover ii.

One side of the oscillator output is grounded to the cover M by the lead 26, and extending substcntlelly st s right sngle from the cover and formed integral therewith is on upper sole treeting electrode is which also serves as a. support upon which a shoe it may rest in cases where it is desirable to secure the heel end of the outsole ii to the heel sect of the shoe prior to the sole attaching operation. v

The insulator plate is is secured by screws is to the front of the upper portion of the cabinet it end serves as a support for the lower sole treating electrode 29 which his within a. groove 28 formed in the upper portion of the insulator plate so that the electrodes are spaced from each other so as to form a slot 22 into which outsoles may be insermd for treatment. The rear portion of the lower electrode 28 is supported by a standon insulator 23 held to the upper wall of the cubinct and it lead 2d connects the electrode to the other or unerounded output side of the oscilietor it.

When the apparatus is made primarily for use with attaching of soles to women's shoes, the electrodes is end 28 may be curved to approximate the shape of e. molded outsole and/or the shoe bottom, end of course they mey be comparatively fist for use with niens work. In any eventthe top of the electrode ill is provided with spaced ribs between which the shoes are placed to prevent overlapping of the outsoles as they are inserted between the electrodes for treatment.

When current is supplied to the oscillator is, high frequency current is supplied to the elecelectrostetic field errists therebetween which, as is well known; will heat dielectric or non-conducting materials such as leather and thermoplastic cements of the types described in the patent to Pitmen, Reissue No. 22,301, and many others such, for example, as those having a neoprene, or Chemigum N or "l-lycer base.

Git

see ess I have found that subjectins only the outsole, with its costing of thermoplastic cement, t th influence of the electrostatic field causes very rapid heating of the outeole end its cement without denser of arcing or burning of th 5919 end that bringing the heated outsole into contact with the cemented shoe bottom while it 1 ,1; room temperature and immediately placing th under pressure in e. shoe press gives excellent adhesion, es the heated cement on the outsole being tacky, immediately adheres to the cool cement on the upper and the transfer of heat soit-= ens the cool cement so that the cements merge endform s homogeneous bond.

I have also found that the cool shoe bottom and its cement rapidly absorbs the host from the heswd outsole cement so that it sets or hardens sufiiicently to allow the shoe to be removed from the sole attaching press after being under pressure for only 8. few seconds and without danger of the sole springing away from the shoe bottom or disrupting the cement bond in any way.

Over at period of years it has been determined that s. minimum bond strength of 4 lbs, per lineer inch is necessary in cemented shoes before e. shoe can safely be removed from the shoe press without danger of the cutsole springing away from the shoe upper, therefore, tests were made by heating the outsoles only, between electrodes for seconds and then pressing them toshoe bottoms at room temperature in e. shoe press at lbs. per square inch pressure. These tests proved that by utilizing the present invention these shoes could be removed from the press in less than 10 seconds without danger of the soles springing away from the shoe bottoms. Efiorts were made to immediately place the shoes in 8. Scott testing machine to determine the bond strength. However, due to time required to place the shoe on the holding fixture and attach the gripper to the outsole, the bond had so seed end the strength thereoi had so increased that it Wes not indicetive of the bond strength at the time the shoe was removed from the press.

To obtein e. compsretive test of bond strength immediatel upon removal of the specimens iron: the-press, strips of leather 1 inch wide end 6 inches long were coated with s. solution oi thermoplestic cement, of the plesticized polyvinyl butyrel type, elong five inches of their length and allowed to dry. The following tests were then made:

One strip was placed in an electrostatic held and heated for 45 seconds, the heated strip wee then removed from the electrodes and immedh utely placed on another strip at room temperature and pressed together at 50 lbs. per square inch for 5 seconds. The uncernented ends were then quickly -e.tteched to-e. spring scale and the strips pulled sport and a bond strength of 5 lbs. per linear inch was obtained. This test was repeated several times and the bond strength obtained varied. between 5 /2 and 8 /2 lbs. per linear inch.

After aging several hours the specimens of the above tests showed at bond strength or over 25 lbs. per iinesr inch.

Another series of tests wos made by piecing both strips in the electrostatic field and heatin them for 45 seconds, removing them from the electrodes and immediately placing them togethor under a pressure of 50 lbs. per square inch. After 5 seconds under pressure a. bond strength of only 1%; lbs. to 2 /2 lbs. per linear inch were obtained. It was found that after 60 seconds in the press a bond strength 01 3 lbs. per linear inch was obtained and it was necessary to leave the specimens in the press as long as 120 seconds before they cooledsumciently to give a bond strength of 5 lbs. per linear inch.

After aging several hours these specimens also showed a bond strength of over 25 lbs. per linear inch.

In the making of shoes in accordance with my novel method'and using the apparatus previously described, the shoe upper is lasted and prepared in the usual manner and the attaching face thereof is coated with a solution of thermoplastic cement which is then allowed to dry.

The outsole is also prepared in the usual manner and the attaching lace thereoi'is coated with a solution of thermoplastic cement which is then allowed to dry.

The outsole may then be attached at its heel end to the heel seat of the shoe by the usual tacks or staples.

The outsole I1 is then inserted in the slot 22 sothat it lies between the electrodes I! and 2|, and the shoe it if attached to the heel end oi the sole is rested on the upper face of the electrode l5. As will be readily understood, only the sole is subjected to the influence oi the electrostatic field existing between the electrodes and heated thereby, and the shoe resting on the upper face of the electrode ll, not being included in the field, will remain substantially at room temperature.

After a normal heating period, the outsole is removed from the treater and another put in its place. The hot outsole is then quickly brought into registry with the cool shoe bottom and the assembly is placed in the shoe press where a pressure of about 50 lbs. per square inch is applied to press the outsole into intimate engagement with the shoe bottom, as is usual procedure.

It can readily be seen that attaching soles to shoes by the method and apparatus above described is a substantial advancement over previously-proposed methods.

It can also be seen that the apparatus described can be made to accommodate several pairs of shoes so that the time required to heat the soles would not delay production.

Since certain changes in carrying out the above process and in the constructions set forth.

which embody the invention. may be made without department from its scope, it is intended that all matter contained in the above'description or shown in the accompanying drawing shall be interpretedas illustrative and not in a limiting sense.

It is also to be understood that the renewing claims are intended to cover all or the generic and specific features of the invention herein described, and all statements of the scope or the invention which, as a matter oi language. mi ht be said to fall therebetween.

Having described my invention, whatI claim as new and desire to secure by Letters Patent. is:

1. That method of attaching outsoles to shoes.

which comprises providing a shoe having its sole engaging race coated with a thermoplastic cement, providing an outsole having its shoe en-;

a thermoplastic cement.

gaging face coated with securing the heel end of said outsole to the heel seat of said shoe, heating the cement on said outsole until it becomes tacky by subjecting it to the influence of an electrostatic ileld while maintaining the cement on said shoe substantially at room temperatur and thereafter pressing said outsole to said shoe until the heated cement on the outsole merges with the cool cement on the shoe.

2. That method of attaching outsoles to shoes, which comprises providing a shoe having its sole engaging face coated with a thermoplastic cement, providing an outsole having its shoe encement oi the other gaging face coated with a thermoplastic cement, attaching the heel end of said outsole to the heel seat or said shoe, heating the cement on only one of said parts by subjecting it to the influence of an electrostatic field while maintaining the of said parts substantially at room* temperature, and thereafter pressing said outsole to said shoe until the heated cement has merged with the cool cement.

HAROLD E..MARASCO. 4 

